Axle driving apparatus

ABSTRACT

In order that a hydraulic pump and a hydraulic motor of a hydrostatic transmission hitherto disposed to the exterior are attached to a hydrostatic transmission support member provided in a mission case, a charging pump hitherto attached to the hydraulic pump at the hydrostatic transmission is also attached to the hydrostatic transmission support member, and an oil filter hitherto attached to the outside of mission case is disposed therein, they are interposed between the lower surface of hydrostatic transmission support member and the charging pump. Furthermore, an outward takeout pump also is supported in the mission case.

.Iadd.This reissue application is a continuation of reissue applicationSer. No. 08/092,685, filed Jul. 16, 1993, now abandoned, and a reissueof application Ser. No. 07/413,763, filed Sep. 28, 1989 (U.S. Pat. No.5,031,403). .Iaddend.

FIELD OF THE INVENTION

The present invention relates to an axle driving apparatus housingtherein a hydrostatic-transmission (HST) used as a driving apparatus fora light running vehicle or the like.

DESCRIPTION OF THE PRIOR ART

Conventionally, for an axle driving apparatus with ahydrostatic-transmission (HST), the following technique has been wellknown as to a hydrostatic transmission support member or a chargingpump:

U.S. Pat. Nos. 4,691,802 and 3,196,696, Japanese Utility ModelPublication No. Sho 52-27345, Japanese Utility Model Laid-Open No. Sho61-134433, Japanese Utility Model Publication No. Sho 56-8735, JapaneseUtility Model Laid-Open No. Sho 60-51351, Japanese Patent Laid-Open No.Sho 61-48661, Japanese Utility Model Publication No. Sho 49-10698, andJapanese Patent Publication No. Sho 63-16630 disclose the followingtechnique respectively.

SUMMARY OF THE INVENTION

The axle driving apparatus of the present invention attaches to ahydrostatic transmission support member provided in a transmission casea hydraulic pump and a hydraulic motor for the hydrostatic transmissionwhich have hitherto have been disposed outside the axle drivingapparatus; attaches a charging pump to the lower surface of thehydrostatic transmission support member; and also disposes an oil filterwithin the axle driving apparatus, so that suction oil passages for thecharging pump are interposed, in condition of communicating with eachother, under the hydrostatic transmission support member. Also, anoutward takeout pump is supported within the transmission case.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional front view of an embodiment of an axle drivingapparatus of the invention,

FIG. 2 is a sectional right side view of the same,

FIG. 3 is a plan view of the same, from which an upper transmission casepart 9b is removed,

FIG. 4 is a sectional plan view of a hydrostatic transmission supportmember,

FIG. 5 is a sectional view taken on the line 5--5 in FIG. 1,

FIG. 6 is a sectional view taken on the line 6--6 in FIG. 1,

FIG. 7 is a perspective view of an oil filter,

FIG. 8 is a sectional front view in part of a modified embodiment of thepresent invention, in which the oil filter is disposed in a differentposition,

FIG. 9 is a sectional front view of a second embodiment of the presentinvention,

FIG. 10 is a partial sectional front view of another modified embodimentof the present invention, in which the discharge oil passage ismodified,

FIG. 11 is a sectional plan view of the hydrostatic transmission supportmember of FIG. 9,

FIG. 12 is a sectional view of the hydrostatic transmission supportmember taken on line 12--12 in FIG. 9,

FIG. 13 is a sectional view taken along line 13--13 in FIG. 9,

FIG. 14 is a sectional front view of a third embodiment of the presentinvention,

FIG. 15 is a sectional front of a still further modified embodiment ofthe axle driving apparatus in FIG. 14, from which the outward takeoutpump is removed,

FIG. 16 is a sectional front view of a fourth embodiment of the presentinvention, and

FIG. 17 is a sectional front view of a embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Next, one embodiment of the axle driving apparatus of the presentinvention will be described in accordance with the accompanyingdrawings.

In FIGS. 1, 2 and 3, a hydraulic pump P and a hydraulic motor M for ahydrostatic transmission in a mission or transmission case 9, ahydrostatic transmission support member 1 for supporting the hydraulicpump P and hydraulic motor M, and a charging pump C attached to thehydrostatic transmission support member 1 are shown and arrangementthereof will be described.

An upper mission or transmission case 9b and a lower mission ortransmission case 9a are vertically connected by connecting bolts toform one mission case 9.

At the mating faces of the lower mission case 9a and upper mission case9b are formed bearing faces for a hydraulic motor shaft 6, acountershaft 38 and axles 17L and 17R.

The hydrostatic transmission support member 1, which is preferablyL-shaped, is connected to the mating face of the upper mission case 9bthrough four bolts B. Between the lower surface of the hydrostatictransmission support member 1 and the inner bottom surface of the lowermission case 9a is formed a space A .Iadd.including an oil sump.Iaddend.for disposing therein a charging pump C to be discussed belowand an outward takeout pump T. At the upper flat surface of thehydrostatic transmission support member 1 is fixed an axial piston typehydraulic pump P for the hydrostatic transmission and at the left sidesurface of a rising portion provided at the hydrostatic transmissionsupport member 1 is fixed a hydraulic motor M of the same type as thehydraulic pump P. Thus, pump P is disposed perpendicular to Motor M.

A closed circuit connecting the hydraulic pump P and hydraulic motor Mfor the hydrostatic transmission comprises crescent-shaped oil passagesP1 and P2 open at the upper flat surface of hydrostatic transmissionsupport member 1, and 1e and 1f also of crescent-shape open at the rightside surface of the rising portion (FIGS. 2 and 4), and two oil passages1c and 1d communicating with these passages P1, P2 and 1e, 1frespectively (FIG. 4).

A hydraulic pump shaft .Iadd.or input shaft .Iaddend.29 perforates theupper mission case 9b so as to upwardly project and a movable swashplate 28 is disposed between the spherical wall of upper mission case 9band the upper surface of hydraulic pump P.

An operational engaging portion projects laterally of the movable swashplate 28 and engages with a lever arm 10 (FIG. 2).

The lever arm 10 is fixed to a speed-change lever shaft 2 and aspeed-change arm 11 is fixed thereto at the position where thespeed-change lever shaft 2 perforates the upper wall of upper missioncase 9b and projects upwardly therefrom.

The movable swash plate 28 is rotated by the lever arm 10 so as tochange the angle of swash plate 28, thereby changing the dischargedirection and a discharge amount of pressure oil from the hydraulic pumpP.

Also, the lower end of hydraulic pump shaft 29 perforates the horizontalpart of hydrostatic transmission support member 1 to enter the space Aand fixedly supports a pump gear 7 of the charging pump C attached tothe lower surface of hydrostatic transmission support member 1. Pump Pfreely rotates on pump shaft 29.

The charging pump C comprises the pump gear 7 covered by a charging pumpcase 3 attached to a lower surface of support member 1. Pump gear 7rotates to pressurize, as operating oil, lubricating oil taken into thecase 3 through an oil filter 5 .Iadd.from the space A oil sump.Iaddend.so that the pressurized lubricating oil is supplied from acharge oil passage 1a to vertical oil passages 1b.

The pump gear 7, as shown in FIG. 6, comprises an internal gear pump ofan internal gear 7b and an external gear 7a, the hydraulic pump shaft 29being fixed at the center of external gear 7a. A crescent shaped shutter7c within internal gears 7b, and engages both gears 7a and 7b, creatingtwo non-engaged spaces 7d and 7e. Lower pressure port 7d communicateswith suction oil passage 3a in order to suck operating oil. Higherpressure port 7e communicates with charge oil passage 1a of supportmember 1.

Check valve seats 41 and 42 communicating with the vertical oil passages1b respectively are disposed so as to form check valves 8 for supplyingpressure oil from the oil passages 1b to the oil passages 1c and 1dbetween the hydraulic pump P and the hydraulic motor M in a closedcircuit.

The check valves 8 can be open by oil pressure from the oil passages 1b,or mechanically as follows: The check valves 8 project at operating endsfrom the side surface of hydrostatic transmission support member 1 and aspring-loaded connecting rod 40 connects and urges against theprojections of the two check valves 8, a push pin 39 for pushing theconnecting rod 40 projects outwardly from the lower mission case 9a.

The push pin is pushed to simultaneously open the check valves 8 so thatthe oil passages 1c and 1d communicate with each other through thevertical oil passages 1b and charge oil passage 1a so as toshort-circuit the closed circuit, thereby stopping rotation of thehydraulic motor M.

Furthermore, the charging pump C is attached to the lower surface ofhydrostatic transmission support member 1 and between the charging pumpcase 3 of charging pump C and the inner surface of lower mission case 9ais interposed a cylindrical oil filter 5 composed of porous material,such as sponge, as shown in FIG. 7.

In order to simplify fixing the unit, the oil filter 5 is not tightenedby bolts, but is sandwiched between the charging pump case 3 and theinner surface of the lower mission case 9a.

The hydraulic motor M fixed to the rising portion of hydrostatictransmission support member 1 obtains torque of the hydraulic motorshaft .Iadd.or output shaft .Iaddend.6 by allowing pistons of the motorM to abut against a fixed swash plate 33. An output gear 34 is fixed toan intermediate portion of hydraulic motor shaft 6, and a braking drum24 of a brake system is fixed to the outer end of the same. Motor Mfreely rotates on motor shaft 6.

As shown in FIG. 3, the output gear 34 fixed to the hydraulic motorshaft 6 engages with a larger diameter gear 35 on the counter shaft 38and a smaller diameter gear 37 thereon engages with a ring gear at adifferential gear D.

FIG. 5 is a bottom view of the hydrostatic transmission support member1, the charging pump case 3 containing therein the pump gear 7 as inFIG. 6.

Operating oil for the charging pump C comprising the pump gear 7 andcharging pump case 3 is taken in by a suction oil passage 3a open at thelower surface of charging pump case 3, the oil filter 5, composed ofcylindrical sponge, is tightly closed around the suction oil passage 3a.

The pressure oil discharged through the pump gear 7 is guided from thedischarge oil passage 3d to the charge oil passage 1a at the hydrostatictransmission support member 1.

Then, the pressure oil is sent from the charge oil passage 1a to inletsof check valves 8 at the check valve seats 41 and 42 through thevertical oil passages 1b.

Usually, during running, high pressure oil is supplied to the oilpassages P1, 1c and 1e or to P2, 1d and 1f, comprising the closedcircuit between the hydraulic pump P and the hydraulic motor M. Assumingthat the high pressure oil is applied to the oil passages P1, 1c and 1e,the pressure oil generated by the charging pump C is lower in oilpressure than the high pressure oil, whereby the check valve 8 is closedwith respect to the check valve seat 41. Hence, the pressure oil fromthe charging pump C does not flow to the oil passages P1, 1c and 1e.

Conversely, when the operating oil in the oil passages P2, 1d and 1fsubjected to a decreased in pressure due to leakage from the hydraulicpump P or the hydraulic motor M and the oil pressure becomes lower thanthat of charging pump C, the pressure at the charging pump C side pushesopen the check valve 8 applied with no pressure, thereby supplying theoperating oil into the closed circuit of oil passages P2, 1d and 1f.

In the modified embodiment in FIG. 8, a small-sized charging pump C isattached to the bottom surface of hydrostatic transmission supportmember 1 and the charging pump case 3 also is small-sized, so that thecylindrical oil filter 5 is interposed outside the charging pump case 3and between the inner bottom surface of lower mission case 9a and thebottom surface of HST support member 1.

Next, explanation will be given on the second embodiments in FIGS. 9,10, 11 and 12.

A hydraulic pump shaft 29 perforates the hydrostatic transmissionsupport member 1 and projects downwardly from the lower surface thereof,passes through the oil filter 5, perforates a shaft bore 3b at thecharging pump case 3 attached to the inner bottom surface of the lowermission case 9a, and engages rotatably with the external gear 7a of thepump gear 7.

The pump gear 7, as shown in FIG. 13, comprises an internal trochoidgear of an internal gear 7b and of an external gear 7a, the hydraulicpump shaft 29 being fixed to the center thereof.

The charging pump C comprises the pump gear 7 covered by a charging pumpcase 3, so that the pump gear 7 rotates to pressurize, as operating oil,the lubricating oil taken in from the oil filter 5 through the suctionoil passage 3a. Pressurized operating oil is supplied to the verticaloil passages 1b of the hydrostatic transmission support member 1.

The check valve seats 41 and 42 are disposed to communicate with thevertical oil passages 1b so that in the check valve seats 41 and 42 areformed check valves 8 for supplying pressure oil from the charging pumpC to the closed circuit between the hydraulic pump P and the hydraulicmotor M.

The check valves 8 project from one side surface of hydrostatictransmission support member and the connecting rod 40 connects theprojections of the two left and right check valves 8. The push pin 39for pushing the connecting rod 40 projects from the lower mission case9a.

The push pin 39 is pushed to open both the check valves 8, whereby thedischarge side and return side of the hydraulic pump P short-circuit tostop the rotation of hydraulic motor M.

At the upper surface of the charging pump case 3 is open the suction oilpassage 3a, around which the oil filter 5 of cylindrical sponge isdisposed.

The operating oil taken in from the suction oil passage 3a is dischargedto part of the discharge oil passage 9d.

The discharge oil passage 9d is recessed in the inner bottom surface ofthe lower mission case 9a, and an oil passage 9e is provided inextension of the discharge oil passage 9d. The oil passage 9ecommunicates with a higher pressure port 7e and the vertical oil passage3c, which communicates with the discharge oil passage 3d at a risingportion of the L-like shape of the charging pump case 3.

The discharge oil passage 3d communicates with vertical oil passage 1bat the hydrostatic transmission support member 1.

Alternatively, the cylindrical and separate oil passage 3d, as shown inFIG. 9, may be a cylindrical separate passage fitted into the case, asshown in the modified embodiment of FIG. 10 in which, the charging pumpcase 3 is if an L-like shaped and an integral discharge oil passage 3dis be bored therethrough.

FIG. 11 is a sectional view of the hydrostatic transmission supportmember 1, FIG. 12 is a bottom view thereof, and the discharge oilpassage 3d is interposed between the bores of vertical oil passages 1bat the hydrostatic transmission support member 1 and the bores ofvertical oil passage 3c at the charge pump case 3.

The pressure oil discharged from the charging pump C is fed from thedischarge oil passage 3d to inlets of check valves 8 at the check valveseats 41 and 42 through the vertical oil passages 1b at the hydrostatictransmission support member.

Next, explanation will be given on the third embodiment in FIG. 14.

The embodiment in FIG. 14 is the same as the former embodiment in thatthe charging pump C is attached to the bottom surface of hydrostatictransmission support member 1, but the hydraulic pump shaft 29perforates the charging pump case 3 and projects therefrom so that atthe position where the hydraulic pump shaft 29 projects from thecharging pump case 3 is detachably mounted a takeout pump T.

The takeout pump shaft 14 is separate from the hydraulic pump shaft 29so as to be removable when the outward takeout pump T is not required.

The takeout pump is similar to charging pump C and includes a takeoutpump shaft 14 supported to a bearing provided at the bottom of the lowermission case 9a and a takeout pump gear 12 for the outward takeout pumpfixed to the pump shaft 14. Takeout pump gear 12, similar to chargingpump gear 7, includes an external gear 12a and an internal gear 12b anda crescent shaped shutter (not shown) which creates two non-engagedspaces lower pressure port 12 and higher pressure port 12e. Port 12dcommunicates with suction oil passage 4a of outward takeout pump case 4to suck operating oil in the mission case 9. Oil filter 5 covers bothcharging pump suction oil passage 3a and takeout pump suction oilpassage 4a.

The pump gear 7 and a pump gear 12 in the drawing are formed as aninternal gear pump, however, the invention is not limited to suchconstruction.

A suction oil passage 4a is open at part of an outward takeout pump case4, so that the operating oil filtrated and taken in the oil filter 5 isguided by the suction oil passage 4a into the outward takeout pump Tand, after being high pressurized, the operating oil is dischargedthrough the discharge pipe 13.

The discharge pipe 13 is charged over in the vertical direction by adirectional control valve V and the operating oil is supplied to a liftcylinder S .Iadd.or hydraulic actuator .Iaddend.or the like at a mowerR, for example.

Return oil from the directional control valve V and lift cylinder S isadapted to return into the mission case 9 through a return pipe 15.

In the further modified embodiment in FIG. 15, the outward takeout pumpT attached to the inner bottom surface of lower mission case 9a in FIG.14 is removed therefrom and only the charging pump C is attached to thebottom surface of hydrostatic transmission support member 1.

In FIG. 16, a fourth embodiment is shown in which onto the inner bottomsurface of the lower mission case 9a is attached an outward takeout pumpcase 4 for the outward takeout pump T and a charging pump case 3 furtheris attached to the upper surface of outward takeout pump case 4.

In this embodiment, both the outward takeout pump T and charging pump C(similar to FIG. 9) are fixed to the inner bottom surface of lowermission case 9a .Iadd.along the longitudinal axis of hydraulic pumpshaft29.Iaddend..

In this embodiment, an oil filter 5 is interposed between the bottomsurface of hydrostatic transmission support member 1 and the uppersurface of charging pump case 3. Takeout pump suction oil passage 4acommunicates with charging pump suctional passage 3a. However, oilfilter 5 covers only the charging pump suction oil passage 3a. Filteredoperating oil is sucked to takeout pump suction oil passage throughcharging pump suction oil passage 3a. Higher pressure port 12e opens tothe inner bottom surface of the mission case 9 at outward takeout port9c.

In FIG. 17, a fifth embodiment is shown in which a charging pump case 3of a charging pump C is fixed to the bottom surface of hydrostatictransmission support member 1 and an outward takeout pump case 4 of theoutward takeout pump T is attached to the lower surface of the chargingpump case 3. .Iadd.In this embodiment, both the outward takeout pump Tand charging pump C are joined to the hydrostatic transmission supportalong the longitudinal axis of hydraulic pump shaft 29..Iaddend.Pressure oil is discharged from the outward takeout pump T to adischarge pipe 13 through a discharge oil passage 4d' and thereafter thereturn oil returns into the mission case 9 through a return pipe 15. Aseparate, cylindrical passage 4d is inserted into passage 4d' betweenthe inner bottom surface of mission case 9, and at takeout port 9c.

An oil filter 5 is interposed between the lower surface of the outwardtakeout pump case 4 and the inner bottom surface of lower mission case9a covering only charging pump suction oil passage 3a. Filteredoperating oil is sucked to oil passage 3a through takeout pump suctionoil passage 4a.

The axle driving apparatus of the present invention constructedaccording to the above-mentioned embodiments is advantageous as follows:

In the space A formed between the hydrostatic transmission supportmember and the lower mission case, the hydrostatic transmission supportmember serves as a baffle plate, so that, even when the vehicle bodyswings, the lubricating oil stays in the space A in a condition which isdifficult to create air bubbles, which can cause a malfunction, such ascavitation, of the charging pump.

Since the charging pump is immersed in the lubricating oil, thelubricating oil cleaned by the filter is directly taken into thecharging pump and not through pipings or the like, whereby there islittle likelihood of line resistance and the suction efficiency isimproved.

Also, since oil leaked from the charging pump can be returned directlyto the space A, it is not required that the pump case be preciselytightly closed, for example, by using an O-ring or the like, whichresults in a lower manufacturing cost.

Since the outward takeout pump T can be disposed in the space A by theaforesaid construction, the axle driving apparatus can be used to driveexternal hydraulic instruments. Also, the oil filter is commonly usablebetween the charging pump C and outward takeout pump T, also loweringmanufacturing costs.

What is claimed is:
 1. An axle driving apparatus comprising,atransmission case; an L-shaped transmission support member housed withinsaid transmission case; a hydraulic pump mounted on said support memberand communicating with an engine; a hydraulic motor mounted on saidsupport member and communicating with an axle; a charging pump disposedon said support member, and driven by said hydraulic pump, said chargingpump including a charging pump discharge oil passage in communicationwith a suction port provided in said support member, and a charging pumpsuction oil passage; and an oil filter covering said charging pumpsuction oil passage.
 2. The axle driving apparatus of claim 1 whereinsaid hydraulic pump is mounted to a horizontal surface of said L-shapedtransmission support member.
 3. The axle driving apparatus of claim 1wherein said hydraulic motor is mounted to a vertical surface of saidL-shaped transmission support member.
 4. The axle driving apparatus ofclaim 1 wherein said charging pump is disposed on a lower horizontalsurface of said transmission support member.
 5. The axle drivingapparatus of claim 1 further comprising,a pair of check valves disposedwithin said support member .[.fluid.]. in a closed fluid circuitprovided within said transmission support member.
 6. The axle drivingapparatus of claim 1, further comprising,an outward takeout pump drivenby said hydraulic pump disposed within said transmission case; a takeoutpump suction oil passage provided in said takeout pump in communicationwith said charging pump suction oil passage; a takeout pump dischargeoil passage provided in said takeout pump, in communication with anoutward takeout port on said transmission case; wherein said oil filtercovers said charging pump suction oil passage and said takeout pumpsuction oil passage.
 7. The axle driving apparatus of claim 6 whereinsaid outward takeout pump is disposed on a inner bottom surface of saidtransmission case.
 8. The axle driving apparatus of claim 1, furthercomprising,an outward takeout pump driven by said hydraulic pump; acharging pump case for receiving said charging pump, fixed to saidsupport member; an outward takeout pump case for receiving said outwardtakeout pump, attached to said charging pump case; a takeout pumpsuction oil passage disposed within said outward takeout pump and incommunication with said charging pump suction oil passage; wherein saidoil filter covers said takeout pump suction oil passage and saidcharging pump suction oil passage; and a takeout pump discharge oilpassage disposed within said outward takeout pump and in communicationwith an outward takeout port on a surface of said transmission case. 9.The axle driving apparatus of claim 8 wherein said charging pump suctionoil passage is open at a lower surface of said .[.changing.]..Iadd.charging .Iaddend.pump case and is covered by said oil filter. 10.An axle driving apparatus comprising,a transmission case; an L-shapedtransmission support member housed within said transmission case; ahydraulic pump mounted on said support member and communicating with anengine; a hydraulic motor mounted on said support member andcommunicating with an axle; a charging pump disposed on an inner surfaceof said transmission case, and driven by said hydraulic pump, saidcharging pump including a charging pump discharge oil passage incommunication with a suction port provided in said support member, and acharging pump suction oil passage; and an oil filter covering saidcharging pump suction oil passage.
 11. The axle driving apparatus ofclaim 10 wherein said hydraulic pump is mounted to a horizontal surfaceof said L-shaped transmission support member.
 12. The axle drivingapparatus of claim 10 wherein said hydraulic motor is mounted to avertical surface of said L-shaped transmission support member.
 13. Theaxle driving apparatus of claim 10 wherein said charging pump isdisposed on a lower surface of said transmission case.
 14. The axledriving apparatus of claim 10 further comprising,a pair of check valvesdisposed within said support member in a closed fluid circuit providedwithin said transmission support member.
 15. The axle driving apparatusof claim 10 further comprising,an outward takeout pump case disposedwithin said transmission case; a charging pump case for receiving saidcharging pump fixed to said outward takeout pump case; an outwardtakeout pump disposed within said outward takeout pump case, driven bysaid hydraulic pump and having a takeout pump suction oil passage and atakeout pump discharge oil passage, wherein said takeout pump suctionoil passage is open at a lower surface of said charging pump case and iscovered by said oil filter, and wherein said takeout pump suction oilpassage is in communication with said charging pump suction oil passage;and an outward takeout port provided on said transmission case andconnected to said takeout pump discharge oil passage. .Iadd.
 16. An axledriving apparatus, comprising:a transmission case; an axle disposedwithin said transmission case; a transmission support housed within saidtransmission case and having a generally horizontal surface; a suctionport provided in said transmission support; a hydraulic motor having ahydraulic motor shaft, said hydraulic motor mounted on said transmissionsupport and communicating with said axle; a hydraulic pump having ahydraulic pump shaft, said hydraulic pump communicating with an engineand mounted to said generally horizontal surface of said transmissionsupport so that said hydraulic pump shaft is disposed substantiallyperpendicular to said hydraulic motor shaft; and a charging pump drivenby said hydraulic pump shaft for supplying oil to said suction port..Iaddend..Iadd.17. The axle driving apparatus of claim 16, wherein saidtransmission support further comprises a generally vertical surface..Iaddend..Iadd.18. The axle driving apparatus of claim 17, wherein saidhydraulic motor is mounted to said generally vertical surface of saidtransmission support. .Iaddend..Iadd.19. The axle driving apparatus ofclaim 16, wherein said charging pump is mounted on said transmissionsupport. .Iaddend..Iadd.20. The axle driving apparatus of claim 16,wherein said charging pump is mounted to said transmission case..Iaddend..Iadd.21. The axle driving apparatus of claim 20, furthercomprising:a charging pump discharge oil passage provided in saidcharging pump; and means disposed within said transmission case forconnecting said charging pump discharge oil passage to said suctionport. .Iaddend..Iadd.22. The axle driving apparatus of claim 16, furthercomprising: an outward takeout pump disposed within said transmissioncase and driven by said hydraulic pump shaft; an outward takeout portdisposed within said transmission case; and an outward takeout pumpdischarge oil passage provided within said outward takeout pump and influid communication with said outward takeout port. .Iaddend..Iadd.23.The axle driving apparatus of claim 22, wherein said outward takeoutpump is disposed on an inner bottom surface of said transmission case..Iaddend..Iadd.24. The axle driving apparatus of claim 22, furthercomprising: a charging pump case fixed to said transmission support forreceiving said charging pump; an outward takeout pump case attached tosaid charging pump case for receiving said outward takeout pump; andmeans disposed within said transmission case for connecting said outwardtakeout pump discharge oil passage to said outward takeout port..Iaddend..Iadd.25. An axle driving apparatus, comprising:a transmissioncase; an axle disposed within said transmission case; a transmissionsupport housed within said transmission case and having a generallyhorizontal surface; a suction port provided in said transmissionsupport; a hydraulic motor having a hydraulic motor shaft, saidhydraulic motor mounted on said transmission support and communicatingwith said axle; a hydraulic pump having a hydraulic pump shaft, saidhydraulic pump communicating with an engine and mounted to saidgenerally horizontal surface of said transmission support so that saidhydraulic pump shaft is disposed substantially perpendicular to saidhydraulic motor shaft; and a charging pump disposed within saidtransmission case and driven by said hydraulic pump shaft for supplyingoil to said suction port. .Iaddend..Iadd.26. The axle driving apparatusof claim 25, wherein said transmission support further comprises: agenerally vertical surface, and wherein said hydraulic motor is mountedto said generally vertical surface. .Iaddend..Iadd.27. The axle drivingapparatus of claim 25, further comprising:an oil sump formed between aninner surface of said transmission case and a surface of saidtransmission support which is opposite to said generally horizontalsurface, wherein said charging pump is disposed within said oil sump..Iaddend..Iadd.28. The axle driving apparatus of claim 27, furthercomprising: a charging pump case attached to said surface of saidtransmission support which is opposite to said generally horizontalsurface for receiving said charging pump; and a charging pump dischargeoil passage provided within said charging pump, wherein said suctionport is open at said surface of said transmission support which isopposite to said generally horizontal surface and is in fluidcommunication with said charging pump discharge oil passage..Iaddend..Iadd.29. The axle driving apparatus of claim 27, furthercomprising: a charging pump case attached to an inner surface of saidtransmission case for receiving said charging pump; a charging pumpdischarge oil passage provided at said charging pump case; and means forconnecting said charging pump discharge oil passage to said suctionport. .Iaddend..Iadd.30. The axle driving apparatus of claim 25, furthercomprising:an outward takeout pump case attached to an inner surface ofsaid transmission case; a charging pump case attached to said outwardtakeout pump case for receiving said charging pump; an outward takeoutpump disposed within said outward takeout pump case, said outwardtakeout pump including an outward takeout pump discharge oil passage;and an outward takeout port disposed within said transmission case andin fluid communication with said outward takeout pump discharge oilpassage. .Iaddend..Iadd.31. An axle driving apparatus, comprising:atransmission case; an oil sump formed with said transmission case; anaxle disposed within said transmission case; a hydraulic transmissiondisposed within said transmission case for driving said axle, saidhydraulic transmission including an input shaft substantially verticallysupported within said transmission case, and a transmission supporthoused within said transmission case; a charging pump disposed withinsaid oil sump, said charging pump driven by said input shaft andincluding a charging pump suction oil passage for supplying oil to saidhydraulic transmission; and an oil filter disposed within said oil sumpand in fluid communication with said charging pump suction oil passage..Iaddend..Iadd.32. The axle driving apparatus of claim 31, furthercomprising: a charging pump case mounted to an inner surface of saidtransmission case for receiving said charging pump, wherein said oilfilter is disposed between said transmission support and said chargingpump case. .Iaddend..Iadd.33. The axle driving apparatus of claim 31,further comprising:a charging pump case mounted on said transmissionsupport for receiving said charging pump, wherein said oil filter isdisposed between said charging pump case and an inner surface of saidtransmission case. .Iaddend..Iadd.34. The axle driving apparatus ofclaim 31, wherein said charging pump is mounted on said transmissionsupport and said oil filter is disposed between said transmissionsupport and an inner surface of said transmission case..Iaddend..Iadd.35. An axle driving apparatus, comprising:a transmissioncase; a transmission support housed within said transmission case, saidtransmission support having a hydraulic pump mounting surface, ahydraulic motor mounting surface substantially perpendicular to saidpump mounting surface, and a charging pump mounting surface separatefrom and substantially parallel to said hydraulic pump mounting surface;a hydraulic pump having a hydraulic pump shaft and mounted to saidhydraulic pump mounting surface; a hydraulic motor having a hydraulicmotor shaft and mounted to said hydraulic motor mounting surface so thatsaid hydraulic motor shaft is disposed perpendicular to said hydraulicpump shaft; a charging pump mounted to said charging pump mountingsurface and driven by hydraulic pump shaft. .Iaddend..Iadd.36. The axledriving apparatus of claim 35, wherein said transmission support issubstantially L-shaped, having a generally horizontal portion whichincludes said hydraulic pump mounting surface and said charging pumpmounting surface and a generally vertical portion which includes saidhydraulic motor mounting surface. .Iaddend..Iadd.37. The axle drivingapparatus of claim 36, wherein said hydraulic pump mounting surface isformed on an upper surface of said generally horizontal portion and saidcharging pump mounting surface is formed on a lower surface of saidgenerally horizontal portion. .Iaddend..Iadd.38. The axle drivingapparatus of claim 37, further comprising: an oil sump formed betweensaid lower surface and an inner bottom surface of said transmissioncase; an oil filter disposed within said oil sump; wherein said chargingpump is disposed within said oil sump and includes a charging pumpsuction oil passage which is open to said oil sump and in fluidcommunication with said oil filter. .Iaddend..Iadd.39. The axle drivingapparatus of claim 38, wherein said oil filter is disposed between saidcharging pump and said inner bottom surface of said transmission case..Iaddend..Iadd.40. The axle driving apparatus of claim 38, wherein saidoil filter is disposed between said transmission support and said innerbottom surface of said transmission case. .Iaddend..Iadd.41. The axledriving apparatus of claim 37, further comprising:a suction port open atsaid lower surface; and wherein said charging pump is disposed withinsaid oil sump and includes a charging pump discharge oil passage influid communication with said suction port. .Iaddend..Iadd.42. An axledriving apparatus, comprising: a transmission case comprising two caseelements joined along a generally horizontal mating surface; a hydraulicpump including a hydraulic pump shaft; a hydraulic motor including ahydraulic motor shaft; a closed fluid circuit connecting said hydraulicpump and said hydraulic motor; a charging pump driven by said hydraulicpump shaft for supplying oil to said closed fluid circuit; atransmission support having a generally horizontal portion and agenerally vertical portion perpendicular to said horizontal portion,said horizontal portion disposed along said mating surface within one ofsaid case elements; a hydraulic pump mounting surface for mounting saidhydraulic pump within said transmission case, said hydraulic pumpmounting surface provided on one side of said horizontal portion of saidtransmission support; a charging pump mounting surface for mounting saidcharging pump within said transmission case, said charging pump mountingsurface provided on a side of said horizontal portion of saidtransmission support opposite to said one side; and a hydraulic motormounting surface for mounting said hydraulic motor within saidtransmission case, said hydraulic motor mounting surface provided atsaid vertical portion of said transmission support. .Iaddend..Iadd.43.The axle driving apparatus of claim 42, further comprising:an oil sumpformed between said transmission support and one of said case elements;an oil filter disposed within said oil sump; wherein said charging pumpincludes a charging pump suction oil passage open to said oil sump andin fluid communication with said oil filter. .Iaddend..Iadd.44. The axledriving apparatus of claim 43, wherein said oil filter is disposedbetween said charging pump mounting surface and an inner surface of saidone of said case elements. .Iaddend..Iadd.45. The axle driving apparatusof claim 43, further comprising:a charging pump case for receiving saidcharging pump, wherein said oil filter is disposed between said chargingpump case and an inner surface of said one of said case elements..Iaddend..Iadd.46. An axle driving apparatus, comprising:a transmissioncase; an axle disposed within said transmission case; a hydraulictransmission disposed within said transmission case, said hydraulictransmission including a substantially vertical input shaft and asubstantially horizontal output shaft operatively connected to saidaxle; a charging pump driven by said input shaft for supplying oil tosaid hydraulic transmission; a common oil sump formed within saidtransmission case common to said charging pump and said axle; and acharging pump case for receiving therein said charging pump, saidcharging pump case disposed within said common oil sump. .Iaddend..Iadd.The axle driving apparatus of claim 46, further comprising atransmission support housed within said transmission case, wherein saidcharging pump case is attached to a lower surface of said transmissionsupport. .Iaddend..Iadd.48. The axle driving apparatus of claim 47,wherein said charging pump is disposed on a lower end of said inputshaft. .Iaddend..Iadd.49. The axle driving apparatus of claim 46,wherein said charging pump case is attached to an inner bottom surfaceof said transmission case. .Iaddend..Iadd.50. The axle driving apparatusof claim 49, wherein said charging pump is disposed on a lower end ofsaid input shaft. .Iaddend..Iadd.51. An axle driving apparatus,comprising:a transmission case having an upper casing and a lowercasing; a pair of axles disposed within said transmission case; adifferential gear for connecting said pair of axles to each other, saiddifferential gear disposed within said transmission casing; a hydraulictransmission disposed within said transmission case, said hydraulictransmission including a substantially vertical input shaft and asubstantially horizontal output shaft connected to said differentialgear; a charging pump driven by said input shaft for supplying oil tosaid hydraulic transmission; and a common oil sump formed within saidtransmission case common to said charging pump and said pair of axles,wherein said charging pump is disposed within said common oil sump..Iaddend..Iadd.52. The axle driving apparatus of claim 51, wherein saidoutput shaft is supported between said upper casing and said lowercasing. .Iaddend..Iadd.53. The axle driving apparatus of claim 51,wherein said pair of axles is supported between said upper casing andsaid lower casing. .Iaddend..Iadd.54. An axle driving apparatus,comprising:a transmission case having an upper casing and a lowercasing; a pair axles disposed within said transmission case; adifferential gear for connecting said pair of axles to each other, saiddifferential gear disposed within said transmission case; a hydraulictransmission disposed within said transmission case, said hydraulictransmission including a substantially vertical input shaft and asubstantially horizontal output shaft operatively connected to said pairof axles; a charging pump driven by said input shaft for supplying oilto said hydraulic transmission; a common oil sump formed within saidtransmission case common to said charging pump and said pair of axles;and a charging pump case for receiving therein said charging pump, saidcharging pump case disposed within said common oil sump..Iaddend..Iadd.55. The axle driving apparatus of claim 54, furthercomprising a transmission support housed within said transmission case,wherein said charging pump case is attached to a lower surface of saidtransmission support. .Iaddend..Iadd.56. The axle driving apparatus ofclaim 55, wherein said charging pump is disposed on a lower end of saidinput shaft. .Iaddend..Iadd.57. The axle driving apparatus of claim 54,wherein said charging pump case is attached to an inner bottom surfaceof said lower casing. .Iaddend..Iadd.58. The axle driving apparatus ofclaim 57, wherein said charging pump is disposed on a lower end of saidinput shaft. .Iaddend..Iadd.59. The axle driving apparatus of claim 54,wherein said output shaft is supported between said upper casing andsaid lower casing. .Iaddend..Iadd.60. The axle driving apparatus ofclaim 54, wherein said pair of axles is supported between said uppercasing and said lower casing. .Iaddend..Iadd.61. An axle drivingapparatus, comprising:a transmission case; an axle disposed within saidtransmission case; a hydraulic transmission disposed within saidtransmission case for driving said axle, said hydraulic transmissionincluding an input shaft substantially vertically supported within saidtransmission case; a takeout pump driven by said input shaft; a commonoil sump formed within said transmission case common to said takeoutpump and said axle; a takeout pump case for receiving therein saidtakeout pump, said take out pump case disposed within said common oilsump; and an actuator external to said transmission case in fluidcommunication with said takeout pump, wherein said takeout pump suppliesoperating oil for said actuator from said common oil sump..Iaddend..Iadd.62. The axle driving apparatus of claim 61, wherein saidtakeout pump case is mounted to an inner surface of said transmissioncase. .Iaddend..Iadd.63. The axle driving apparatus of claim 62, whereinsaid takeout pump is disposed on an end of said input shaft..Iaddend..Iadd.64. The axle driving apparatus of claim 61, furthercomprising: a transmission supported housed within said transmissioncase, wherein said takeout pump case is mounted on a surface of saidtransmission support. .Iaddend..Iadd.65. An axle driving apparatus,comprising:a transmission case; an axle disposed within saidtransmission case; a hydraulic transmission disposed within saidtransmission for driving said axle, said hydraulic transmissionincluding an input shaft substantially vertically supported within saidtransmission case; a takeout pump driven by said input shaft; a commonoil sump formed within said transmission case common to said takeoutpump and said axle, said takeout pump disposed within said common oilsump; an actuator external to said transmission case; an outward takeoutport disposed within said transmission case in fluid communication withsaid actuator, wherein said takeout pump supplies operating oil for saidactuator from said outward takeout port; and a return pipe connected tosaid transmission case for returning takeout oil from said actuator intosaid transmission case. .Iaddend..Iadd.66. The axle driving apparatus ofclaim 65, wherein said outward takeout port is open at a lower surfaceof said transmission case. .Iaddend..Iadd.67. The axle driving apparatusof claim 65, wherein said return pipe is in fluid communication withsaid oil sump. .Iaddend..Iadd.68. The axle driving apparatus of claim67, wherein said return pipe is open at a bottom of said transmissioncase. .Iaddend..Iadd.69. The axle driving apparatus of claim 65, furthercomprising:a takeout pump case for receiving therein said takeout pump,wherein said takeout pump case is mounted to an inner surface of saidtransmission case. .Iaddend..Iadd.70. The axle driving apparatus ofclaim 65, wherein said takeout pump is disposed on an end of said inputshaft. .Iaddend..Iadd.71. The axle driving apparatus of claim 65,further comprising: a takeout pump case for receiving therein saidtakeout pump; a transmission support housed within said transmissioncase, wherein said takeout pump case is mounted on a surface of saidtransmission support. .Iaddend..Iadd.72. An axle driving apparatus,comprising:a transmission case; an axle disposed within saidtransmission case; a hydraulic transmission disposed within saidtransmission case for driving said axle, said hydraulic transmissionincluding an input shaft substantially vertically supported within saidtransmission case; a charging pump driven by said input shaft; a commonoil sump formed within said transmission case common to said chargingpump and said axle; a charging pump case for receiving therein saidcharging pump, said charging pump case disposed within said common oilsump; a takeout pump driven by said input shaft; a takeout pump case forreceiving therein said takeout pump, said takeout pump case disposedwithin said common oil sump; and an actuator external to saidtransmission case in fluid communication with said takeout pump, whereinsaid charging pump and said takeout pump suck up oil within said commonoil sump, said charging pump supplying operating oil for said hydraulictransmission, and said takeout pump supplying operating oil for saidactuator. .Iaddend..Iadd.73. The axle driving apparatus of claim 72,further comprising: a transmission support housed within saidtransmission case, wherein said charging pump case and said takeout pumpcase are disposed between said transmission support and saidtransmission case. .Iaddend..Iadd.74. The axle driving apparatus ofclaim 73, wherein said takeout pump case is mounted to said transmissioncase and said charging pump case is mounted to said transmissionsupport. .Iaddend..Iadd.75. The axle driving apparatus of claim 73,wherein said takeout pump case and said charging pump case are disposedalong the longitudinal axis of said input shaft and are joined to saidtransmission support. .Iaddend..Iadd.76. The axle driving apparatus ofclaim 72, wherein said takeout pump case and said charging pump case aredisposed along the longitudinal axis of said input shaft and are joinedto said transmission case. .Iaddend..Iadd.77. An axle driving apparatus,comprising:a transmission case; an axle disposed within saidtransmission case; a hydraulic transmission disposed within saidtransmission case, said hydraulic transmission including a substantiallyvertical input shaft and a substantially horizontal output shaftoperatively connected to said axle; a charging pump driven by said inputshaft for supplying oil to said hydraulic transmission; a common oilsump formed within said transmission case common to said charging pumpand said axle; a charging pump case for receiving therein said chargingpump, said charging pump case is attached to a bottom surface of saidtransmission case; and an oil passage for supplying discharged oil fromsaid charging pump to said hydraulic transmission, said oil passage isdisposed within said common oil sump. .Iaddend..Iadd.78. An axle drivingapparatus, comprising:a transmission case having an upper casing and alower casing; a pair of axles disposed within said transmission case; adifferential gear for connecting said pair of axles to each other, saiddifferential gear disposed within said transmission case; a hydraulictransmission disposed within said transmission case, said hydraulictransmission including a substantially vertical input shaft and asubstantially horizontal output shaft operatively connected to said pairof axles; a charging pump driven by said input shaft for supplying oilto said hydraulic transmission; a common oil sump formed within saidtransmission case common to said charging pump and said pair of axles; acharging pump case for receiving therein said charging pump, saidcharging pump case is attached to a bottom surface of said transmissioncase; and an oil passage for supplying discharged oil from said chargingpump to said hydraulic transmission, said oil passage is disposed withinsaid common oil sump. .Iaddend..Iadd.79. An axle driving apparatus,comprising: a transmission case; an axle disposed within saidtransmission case; a hydraulic transmission disposed within saidtransmission case for driving said axle, said hydraulic transmissionincluding an input shaft substantially vertically supported within saidtransmission case; a charging pump driven by said input shaft; a commonoil sump formed within said transmission case common to said chargingpump and said axle; a charging pump case for receiving therein saidcharging pump; a takeout pump driven by said input shaft; a takeout pumpcase for receiving therein said takeout pump, wherein said charging pumpcase and said takeout pump case are along the longitudinal axis of saidinput shaft and are joined to a bottom surface of said transmissioncase; and an oil passage for supplying discharged oil from said chargingpump to said hydraulic transmission, said oil passage is disposed withinsaid common oil sump. .Iaddend.